* Choose the letter A, B or C to complete the passage below. People need air to breathe. In order to keep us heathy, we need (1)__________ air. However, nowadays, (2)_______ lot of things in our lives create harmful gasses and make the air dirty, like factories, cars and motobikes. Air (3)______ is one of the worldwide alarming issues nowadays. It causes not only (4)________ problems in people but also in plants and animals. Its our responsibility to keep the air (5)________. 1. A. clean. B. dirty. C. polluted. 2. A. a. B. the. C. an 3. A. pollute. B. polluted. C. pollution. 4. A. health. B. unhealthy. C. healthy. 5. A. dirty. B. unpolluted. C. harmful.